Energy management is a key problem area for mobile terminals. The battery lifetime is a distinguishing feature of the mobile phone and is a very important aspect that affects a mobile telephone's usability. As long as mobile telephones were constructed using proprietary software platforms that were inaccessible to third party developers, the manufacturers had a great deal of control over the energy usage patterns of their own internally developed applications. However, this situation has changed greatly in recent years. New widely-adopted software platforms such as the Symbian operating system and Java-based runtime environments have been created, and third party developers can now deploy their applications to mobile telephones. As a result, manufacturers can no longer test, in advance, each application that is run on their mobile telephones. Consequently, the danger of malicious or faulty applications being run on mobile telephone is greater than ever. To address this threat, manufacturers must enhance their mobile software platforms to protect key hardware resources in general, battery lifetime in particular.
An example of a current mobile software platform is OSGi. OSGi, which stands for “Open Services Gateway Initiative” and is discussed at www.osgi.org, is an open, common architecture to deploy and manage services in a coordinated manner. OSGi provides a general-purpose, secure, managed Java-based framework that supports the deployment of extensible and downloadable service applications known as bundles. OSGi-compliant devices can download and install OSGi deployment entities and remove them when they are no longer required. Installed and started bundles can register a number of services that can be shared with other bundles under strict control of the framework.
OSGi can run on the top of a standard Java Virtual Machine (VM). Contrary to conventional methods where one Java application runs on one VM, several bundles can be run simultaneously on the same VM in OSGi. OSGi as a multi-application platform assumes a mostly cooperative environment, where the installed applications behave according to the rules/guidance described in the OSGi specification. Although this assumption may hold true in a closed environment where all installed applications come from a trusted source, it may not be true if the platform may run any application, even those whose source is not trusted.
OSGi currently does not mandate a resource management solution. Consequently, applications are not separated or controlled as far as resource usage is concerned. “Resource” refers to both physical resources, such as processor time, primary and secondary storage, network bandwidth, battery energy, etc., and logical resources, such as databases, various UI components, etc. in OSGi systems. If the application resource usage is not controlled, the platform is open to Denial of Service-type attacks. In such circumstances faulty and malicious applications exploiting the lack of resource management directly endanger the robustness, reliability, and usability of the platform.
With plans to deploy the OSGi platform to mobile phones, the issue of energy management becomes much more complex. With no resource management system in place and no limitations on the energy usage of OSGi applications, ill-behaving applications may simply drain the battery power by repeatedly performing energy-intensive operations. For example, such applications could control the display backlight, play tones, perform network communications, etc., rendering the phone virtually unusable by dramatically shortening the battery lifetime.